1. Waves
Physics Mr. Berman
Greece 2005, North Aegean Sea

2. Waves and their characteristics
Velocity of a wave
Types of waves

3. Oscillation
Object moves back and forth about an equilibrium position.

4. Pulse: A single disturbance travelling through a medium.

5. Wave Train (Travelling Wave or simply wave):
A series of pulses at regular intervals.

6. Wave on a String
(Applet)

7. Graph of Displacement vs Time

8. Displacement vs Distance Traveled

9. Speed of a Wave, v
v= d/t
v = l/T v =lf

10. Types of Waves
Transverse
Longitudinal

11. Transverse (ex: waves along a string, electromagnetic waves).
The particles vibrate perpendicular to the direction of the wave's propagation
(ex: waves along a string, electromagnetic waves).

12. Example: S Earthquake Wave

13. Longitudinal Waves
The particle displacement is parallel to the direction of wave propagation (ex: sound)

14. Torsional Waves
Video link on Web : Collapse of Takoma Narrows Bridge, Washington State, 1940

15. Elliptical Waves
Result when longitudinal and transverse waves are superpositioned.
(ex: surface water waves)

16. Ocean Wave

17. Ocean Wave

18. Note Waves transfer of energy from one point to another.
Waves do not transfer matter.

19. Types of Waves
Mechanical Waves
Electromagnetic Waves

20. Mechanical Waves require a medium.
Examples:
Water waves( Tsunami)
Sound waves (v= 340 m/sec in air but varies for different media)
Earthquake waves

21. Electromagnetic Waves do not require a medium and can travel through the empty space (vacuum).
Example: 
Light from the sun travels through space and reaches us.
Note: All EM waves have a speed through vacuum of 3 x 108 m/sec.

22. Problem 1
What is the distance a sound wave in air traveled in 2 sec? Answer: 680m/s

23. Problem 2
What is the frequency of a light wave of wave length 550x 10-9 m?
Answer: 5.5 x Hz

24. Problem 3
A SONAR (Sound Navigation and Ranging) sends a signal to the bottom of the ocean. The speed of sound in water is 1435 m/s. If the signal echo returned in 0.4 sec, how deep was the water?
Answer: 287m